It is known that naturally-occurring algae can be used as biosensors for primary-source drinking water protection. For example, U.S. Pat. No. 6,569,384 to Greenbaum et al. describes a method for monitoring the variable fluorescence of algae that live in primary-source waters. Greenbaum et al. discloses using altered patterns of the fluorescence induction as a method for detecting the presence of toxins. Until now, the method used for assessing the presence of a toxin is to use standard numerical parameters that are derived from only two (2) specific points of the variable fluorescence induction curve. Software for obtaining these parameters is generally provided by the instrument manufacturer.
FIG. 1 shows a typical variable fluorescence induction curve from naturally-occurring algae in untreated river water. It can be seen from FIG. 1 that fluorescence emission during light activation is a time-dependent process. In particular there is an initial fluorescence, Fo, and a maximum fluorescence Fmax. As shown in FIG. 1, the photochemical efficiency, Y, is generally calculated from the initial and maximum fluorescence values. It is known that specific toxins that can harm humans will alter the photochemical efficiency, Y. It is this alteration that is used as the signature for the presence of toxins. See, e.g., Rodriguez, Jr., M., Sanders, C. A. Greenbaum, E. 2002. “Biosensors for rapid monitoring of primary-source drinking water using naturally occurring photosynthesis”, Biosensors and Bioelectronics, 17(10):843-849.
Accordingly, only two points (Fmax and Fo) of the chlorophyll fluorescence induction data are actually utilized. As a result, the information derived generally lacks sensitivity and speed in detecting and identifying potentially toxic agents, thus rendering the procedure to have limited value. What is needed is a methodology to utilize a larger portion of the data generated to provide improved sensitivity and speed in detecting and identifying potentially toxic agents.